Telephone system.



No. 885,270. PATENTED APR. 2l, 1.908. 1:". E. MAYBBRRY & N. H. HOLLAND.

TELEPHONE SYSTEM.

APPLICATION FILED APB.12`,1902.

3 SHEETS-SHEET 1.

` No. 885,270. PATEN'IED APR. 21, 1908.

F. E. MAYBERRY & N. H. HOLLAND.

TELEPHONE SYSTEM.

APPLIOATION FILED APR.1z,19oz.

3 SHEETS-SHEET 2.

u/,zgvs ses; l QU/67112776 f mmw D34 Z, @75711717 7/zj erij 1 QJfewymm, maken,

No. 885,270. l v PATENTED APR. 21, 1908. F. E. MAYBBRRY & N. H. HOLLAND.

TELEPHONE SYSTEM.

APPLIOATION FILED APR.12,1902.

3 SHEETS-SHEET 3.

i UNITED STATES PATENT OFFICE.

FRANK E. MAYBERRY, OF WEST MEDFORD, AND NEWMAN H. HOLLAND, OF BROOKLINE, MASSACHUSETTS, ASSIGNORS TOBOSTON TELEPHONE SELECTOR COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MAINE.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented April 21, 1908.

To all whom it may concern:

Be it known that we, FRANic E. MAY- BERRY and NEWMAN H. HOLLAND, of West Medford, county of Middlesex, and State of Massachusetts, and Brookline, county of Norfolk, and State of Massachusetts, respectively, have invented an Improvement in Telephone Systems, of which the following description, 1n. connection with the accompanying drawings,`is a specification, like letters on the drawings representing like parts.

- selecting `or controlling instrument ada ted to be set .by a. certain definite number o impulses of current in one direction and restored by`an impulseV of current 1n the opposite direction.-

The-system to which.the invention relates is shown and described in Patent No. 691,281,A granted to FrankE. Mayberry Jan. 14, 190,2, and the present'invention re improvements in the local-instrument and y also in thedevices located ,at the central oflce for utilizing the selecting devices.

In, accordance With.- the invention, the instruments located at the several stations are each arranged to be .operated by a single electro-magnet .having two coils, the same magnetalsobeing utillzed to operate the signal, tlre selecting .mechanism 'being controlled by current from a source of current at the central oflice, while the signal may be' given by a bell striker operated inthe usual way, by an .alternating current flowing through the same magnet coils. The electro-magnet a't each instrument is provided for this purpose with two armatures, in additlon to the usual signaling or bell striker armature; and the sald armatures are respectively adapted'to control an operating /pawl and a retaining pawl, the mechanism being provided with a restoring spring which isv adaptedto restore the parts. to normal position when the retaining pa'wl has been re- The bell striker or equivalent signaling device mechanically controlled by means of the' selecting mechanism, so that, although ates mainly to influenced by current from a central officeAv permit .the operation `oi the signaling device.

The same. selecting mechanism is likewise arranged lto control the. closure of the telephonecircuit at each station, so that when the line is in use it is impossible for any sbscriber except the one at the station `where* the telephone is in use to connect his local telephone circuit with the line.

.The invention further relates to a novel arrangement for signaling central office and for automatically locking out the other telephones along the line on which the signal has been originated, a third conductor being utilized for this pur 'ose which .ma conveniently be a ground? since it is tota 1 disconnected from the line when the telephones are in use.

Afurther feature of the invention consists in means for restoring the several controlling instruments to normal in response to a device under the control of the operator, such as. the ordinary switch hook, which is operated by hanging up the receiver, and 1t is desirable and practicable, though not essential, to arrange the system so that the instruments will `not be restored until both receivers have been hung up; so that if a subscriber should inadvertentl hang up his receiver before he had finislie sation, he would still maintain control of the line unless the party with whose station he was connected should also hang up his recelver.

Figure 1 is a front elevation of one of the instruments located at a station; Fig. 2 is a side elevation of the same; Fig. 3 is a horizontal section on line ac3 of'Fig. 1;,F ig. 4 a partial plan view; Fig. 5 a diagram of circuits at the central olice illustrating a signaling mechanism of novel constructlon and arrangement; and Fig. 6 a diagram showing line and central oflice connections by means of which the restoring of thev instruments on d his convertwo connected lines is dependent upon the hanging up ofthe receivers.

In the telephone system embodying the present invention, eac station along the line 1s provided with an instrument arranged to be controlled from central olice, the several instruments along a line being operated by impulses of current sent from a source at the line by an impulse of current in the opposite direction.

In accordance with the present invention the instrument located at the sub-station is provided with an electro-magnet having two coils a bridged across the line, as shown in Fi s. 5 and 6, and the Amagnet commonly uti ized to operate a bell striker may be employed for the purpose. As herein shown, the magnet coils a are provided with a polarized armature b pivoted at b2, and provided with a bell striker d, the said armature being polarized by the influence of a permanent magnet c. Thus an alternating current traveling over the line (the magnet coils a being permanently bridged across the line) will tend to set the 'armature b and the belll striker d in vibration to give a signal.

In order to prevent the operation of the signal, however, at all stations along a given line except the one selected, the bell striker is rovided with a mechanical stop e which' is llierein shown as a disk mounted on a shaft e2 supported by bearings e3 so as to be capable of rotation. The said disk e is so related to the armature b which is connected with the bell striker d as to engage the said armature, so that the movement of the said armature is preventedvunder normal conditions. To permit the `movement of the armature, however, each disk is provided with a notch or opening e4, Fig. 4, the disks at the several stations having the notches differently placed, so that if the said disks are rotated in unison at all the stations until the notch in the disk atone station is in line with the armature b at said` station, so as to permit the vibration of the said armature, the notches in the disks at all the other stations will be out of line with the respective armatures at said stations so as to prevent the operation of the signal at any of said stations.

As herein shown, the locking disk is located between the limits of movement of the vibrating armature l), so'that it will prevent the movement thereof whether the vprojecting portion of the armature is above or below 'the disk, it being, therefore, immaterial in which position the said armature may stop after. a signal has been rung in.

The several disks along a given line are arranged to be operated in unison, by a stepl by step movementin response to impulses of currentina given direction flowing over the das state i.

line from central office through the electromagnets at the several stations, the said electro-magnets being bridged across the line, Thus a certain definite number of impulses rotating the disks e at all the stations will bring the notch e4 in the disk at the right station in position to permit the vibration of the armature b, so that when current ofthe proper character is subsequently sent over the line the signal will be given only at the selected station, since the armatures at the other stations are prevented from vibratingv in response to the action of the current.

To restore the several disks e to normal,

Aeach disk is provided with a restoring device such as a motor spring e5, and is acted upon by a retaining pawl which pawl is adapted to be released or disengaged from the teeth of the ratchet wheel e6 connected with .the disk e in response to an impulse of current flowing over the line through the electro-magnet coils a in the opposite .direction from that utilized in propelling thedisks in their forward .direction against thev stress of thev The propelling pawl fand the resprings.

taining pawl g are controlled respectively byv armatures f2 and g2, and in order to obtain the proper action in response to impulses of4 f current differing in directionor polarity, at

least one ofthe said armatures is polarized,

it being unnecessary, however, to polarize both, as wilLbe explained.

As herein shown, the armature g2 whichv operates the releasing pawl .g is polarizedfit4 being practicable to locate the said armature, as shown, in proximity to the permanent `magnet c which is used to. polarize the armature b, so that only one permanent magnet,

and that the one usually employed in connection with a magneto bell, need be used.

The polarity of the armature g2 is such tnat when an impulse of current iowing in the right direction to pro el the `disks e forward,

passes over the line, t e said armature, which.'

is pivoted betweenthe two coi1sa',fwill be `rocked on its pivot tothe positionshown in Fig. 3, thus moving the ment with the teethiof t The same impulse of current will attract the armature f2, causing. the pawl f to engage lpawl q into engagewith a tooth of the ratchet wheel e movingthe saine` onev step, as indicated in dotted lines Fig. .3.7 i The armature g2 is provided with a spring or yielding connecting device g3 to permit the e ratchet wheelwe".

retaining pawl q to ride over the ratchet teeth` as indicated when the said armature is in the position shown in Fig. 3. It is obvious' that this action will takeplace each time an impulse of current in the right direction is sent over the line, so that all the disks will be forwarded an equal distance so as .to permit the operation -i f of the signaling device at one instrument only The armature g2 is balanced on its pivot, and its movement is prevented when uninfluenced by current on account of its proximity to one of the poles of the magnet a, so

' that the retaining pawl g re yrains in engagement-with a tooth ot the ratchet wheel e" until it hasA been released after the subscriber has.

-turef is provided with a restoring springf,

so that as soon as the current ceases, the said varmature will be retracted or moved to the full line position, Figs. 3 and 4, the pawlf being pivotally connected wit-h the said armature and arranged to be engaged by a stop f4 which throws it out of the path of the ratchet teeth. The armature gwill, as stated before, remain in either position, and consequently will hold the retaining pawl g out of engagement with the teeth of the ratchet wheel e, permitting the disk c to return to its normal position through tlie agency of the spring or equivalent device e". The normal position of each disk is controlled by a suitable sto In or( er 'to prevent the release of the several disks in response to the action ot the signaling current which passes through the magnet coils a and which might influence the armature g2, theA armaturejf is provided with a locking devicef5 adapted to engage the end of the armature g2 when the armature f1 is retracted, and thereby hold the same in the position shown in Fig. 3.

The armature f2 being non-polarized and "also provided with the restoring spring f,

Cil

will not respond yto the signaling current, but will remain in its retracted position, and'will revent the movement of the armature he said armature f2, however, as stated, `will respond to the impulse ol" current used for restoring, and will consequently unlock the armature g2 and' permit the same the position shown in Fig. 4; f

. To revent the use of the telephone at any exclu ed station on the line, each controlling device is `arranged tof cooperate with the switch hook h or--equival'ent device which closes the telephone circuit, so that the said switch hook will not move even if the receiver'is taken down.` Forthis purpose a stop arranged to cooperate with the switch hookh', the said stop being'sh'own as a disk similarito the 'disk e, y'and mounted on the shaft e2 in proximity to the switch hook h. Each disk Iitis provided with two openings fi land j, t e opening normally standto ymove to ing in line with a projection h2 y from the switch hook so as to receive the said projection if the receiver is removed and permit the said switch hook to be raisedi If, however, the disk has been moved from its normal position it is obvious that the opening will be moved out ot' alinement with theprojection h2 so that the tace of the disk will engage the sa'id projection h2 and prevent the switch hook h from rising. The openings j* are dit'- ferently located so asv to correspond with the different locations ol the notches or openings e4, so that when the notch e* is in such position that a signal can be received, thel opening j at the same instrument will be over the projection 7i, so that the telephone circuit can be closed. ll", therefore, a subscriber desires to call up central otlice he can talte down his receiver and connect in his telephone, since the switch. hook zy will rise because the opening fis in the proper place, and il he has received a call l'rom central he can use his telephone because the opening j has been placed in the proper position prior to the receiving of the calling signal.

While the `instrument herein-before described is intended for use with a local battery system, thc magnetos at thesub-stations maybe dispensed with, and the calling signal displayed at central in respons(` to the act oll the subscriber in closing the telephone circuit,

by taking down thereceiver. .ln addition to tlie signaling at central, moreover, the taking down ol the receiver causes an impulse'ol current to travel over the line, on which the station is located, in the proper direction to move the several instruments one step forward so thateach instrument is locked out, it being impossible, therefore, for the subscriber` at any other station to connect hisinstrument withthe line. The calling instrument, however, is not ail'ected by this impulse of current,l since the projection h2 is arranged to engage the opening before the impulse of current travels over' the line, so that the disk at the calling station is mechanically prevented from rotating.

Ret'egring to Fig. 5 which shows one arrangement whereby the desired results are attained, the source ol' current used for operating the several selecting instruments' is shown as a battery C located at the central office, one terminal of said battery being connected withthe groundyas indicated at G, while the other terminal is adapted to be connected with one ol' the line conductors, the other line conductor being arranged to be grounded. It may be noted in this connection'that the ground constitutes a third conductor, which might of course be metallic it' desired. 'lhc ground connection, however, answers everyY purposeffand is not objectionablesince it is totally disconnected from'the regular line conductors at all the sub-stations when the telephones are in use.

sented as the coils a)which are bridged across the. line in multiple, to the conductor A and thence to ground at G2, the currenttraveling through the several instruments in the direction indicated by the arrow-which is the right direction to operate the pawl Thus, .when the receiver is taken ,down at any station the disks e at all the other stations on the same line are given one forward movement so as to lock out all the telephone instruments along said line. The same battery C is utilized to operate a. signal at the central olice such as a lamp H, the lighting of which is controlled by a switch member H2 connected with an armature H3 pivotally supported between the poles of two electromagnets H4 and H5'so as to be moved in one direction or the other if either of the said coils is energized. The armature H3 is shown in normal position in Fig. 5.

The grounding of the line A, which has been described, also temporarily closes a circuit froin the batt-ery C through conductors 1, 2, 3' and 4, to the coil H4, conductor 5, to line A and back to ground at G2. This causes thev armature H3 to be attracted by the coil H4, thus closing a' circuit from the battery through conductor 1, 2, 3, switch member H2 and conductor 7, (the latter conm taining the lamp H) to ground at G3. This .notifies central of the calland the answering plug n, n2 is then inserted in the ack-mf, m2, thus disconnecting the direct path from ba-ttery C to line B at contact m2, so that any further movement of the receiver will have no effect on the .several instruments. After ytwo lines have been connected by the subsequent insertion of the callingplug N, N2 into the jack of the line called for, the proper station on the said line is selected by the necessary number of impulses sent over the line by the operator at central office.

The means for sending out the necessary number of impulses to select the station on the line called are herein indicated in diagram as consisting of two table keys o, o2 and p, p2, the former controlling the impulses of battery current and the latter controlling the signaling impulse from the magneto'M.

The principle involved is substantially the same as that shown and described in the prior patent to F. E. Mayberry herein-before cited, and does notl Jform any present invention, being merely included in the illustration for the purpose of insuring a art of the clear understanding of the invention involved in the present application. The operation is will connect the tip terminal N 2 and the conductor B of the same line with the battery. This will cause an impulse of current to flow over the said line corresponding in direction to the impulse of current already described in connection with the calling line, and indicated by the arrow, and the operation of the key theright number of times will thus result in the selection of the desired station. The subsequent manipulation of the table key p, p2 will then connect the magneto with the line on'which the called station is located so as to give.l the necessary signal. It is to be understood that this method of calling is illustrated herein merely to aord a proper understandin of the present inventlon, a more practica method of accomplish-ing this purpose being shown and described in another application iled herewith.

The clearing out signal g is controlled by a magnet q2 which is energized When the re-v ceiver is hung up by current in a circuit completed by groundin the line A momentarily. The circuit is as iol ows: Battery C, conductors l, 2, 3, 4, and 8 (including magnet coil H5) to jack terminal m2, which when the plu is inserted is in contact with the termina ma, conductor 9l to magnet g2, conductrl() .to sleeve terminal, which connects with line A, which, as has been stated, Vis momentarily grounded by the hook when the receiver is hung up. This does not, however, extinguish .the signal lamp H, since there is another more direct circuit through conductor 5 and line A to ground, which includes the magnet .coils -H4, the said coils H4, therefore, being energized to a greater extent than the coils H5, which, as shown above, are in seriesA with the clearing out magnet g2. l V

Upon receiving theclearing out signal the operator restores the' instruments on both lines to normal by sending a current from the battery C over the lines'through all the coils a in the direction o by means of a table key r, r2 which grounds the line wire B at Gf4 and'con'nects -thevlin'e conductor A with the battery through. the' conductors 13, 2 and 1. s y v Tn order that the system may 'be installed at the central oilice without materially changing the existing circuits, the table key r, r2/is placed in the circuit of the operators set, as

shown, and isa'dapte'd to -be connected into any of the cord circuits through the agenc ofthe ordinary listeningin key Withwhich p'osite tol that indi. cated by the arrow. T 1s is accomplished- Y,

` fore, only to add the table key p", r2 in connection withthe operators set, as indicated, so that one only of vsuch restoring keys is suilicient for a complete operators position, since it can be connected with any cord circuit through the existing listening-in key belonging to saidcord circuit.

IUpon receiving the clearing out signal, therefore, `the operator' will press the listening-in key as 4is customary, and u on finding that the subscribers have finisher their conversation she will operate the restoring key r, r'thus sending an impulse of current over both lines in the right direction to restore the storing key. r, r2 also controls the signal lampv instruments.

'The`restoring circuit may be traced as follows: Battery C', conductors 1, 2 and 13, Switch terminal 17, conductor 1.4, switch terminal s, line c onductor A, thence through the several instruments in the direction opposite to that indicated by the arrowto the line conductor B, tip terminals m2 audaz. conductors 1() and 15, y.switch terminal s2, switch terminal r2 to ground G4. The re- H by completing a circuit through the electro-magnet H5 as follows: Battery C, conductors 1, 2, 3, 4, coil IP, cfonductor 8, terminals m, m2, tip terminal n.2, conductors 1U.

and 15, switch terminal si, switch terminal r2 to ground G4. "lhere is another path for the currentv Jfrom the batteryY`v through the maunet coil H4 and the conductor 5 to the line and thence through the several instruments to the line B and back to ground as above traced, it being obvious, however, that since' this path includes the instruments along the line it will be of much higher resistance than that of the direct path through the electromagnet H5, so, that the latter will attract the armature H3 and break the lamp circuit through the conductor 7. Since the signal lamp H will not be put out until the restoring key r, r2 has been operated, thefsaid lamp serves as a reminder to the operator and tends to avoid the possibility of neglect in restoring 4the several instruments to normal after conversation has been finished.

A further :feature of the invention is embodied in means for automatically restoring the instruments to normal without the intervention of the operator atcentral o'llce. A diagram illustratii'ig this feature is shown in Fig. 6, and 'lor purposes of illustration a system somewhat analogous to a double lcentral as previously described.

by the momentary 4grounding the line A as the switch hook passes the contact before a plug has been inserted in the jack at central causes the instruments on the sameline to be locked out and a signal to be operated at p This circuit is as follows; Battery C, conductors 1, 2 to switch terminals 2 and 2b, conductor 2?,

.calling si nal magnet 2f conductor 2e ti Y D 7 terminal m2 line and through the'several instruments along the said line to the line A, and ,to rround G2, the circuit being momentarily c osed as the switch 71, passes the grounded contact. struments along the calling line, and operates the calling signal, the said calling signal or drop being so arranged as to break the circuit at Qaand 2b, as indicated, so that any further movement of the receiver hook prior to the restoring of the drop or the in-sertion of the plug at the central oil'ice will have no further ellect on the instrunients along the line. After the plugs are in, the hanging up of the receiver at either-station will operate a clearing out drop, there being, however, a

'clearing out drop for each of two connected lines,'while the circuit for current through the instruments in the opposite direction for restoring them is not completed until both clearing out drops have been operated. The hanging up of a receiver, for example, on the line illustrated will close a rircuit as follows: Battery (l, conductor 1, conductor 16, clearing out drop magnet 16", sleeve terminal, n, line A, to ground G2, thus operating the clearing out drop belonging to that line.

The clearing out drop operates as a circuit closer to connect a conductor 17 leadinfr from the tip wire, with a comluctor 1S, which is adapted to be connected with the ground through conductor v19, through the agency of the clearing out drop controlled by the electro-magnet 16,l which belon s to the other line, and which is operate through conductorI 16A., etc., when the receiver on that line is hung up.-

lt is obvious, therefore, that the tip conductor will not be grounded until both clearing out drops have been operated, indicatin that both receivers have been hung vup an the conversation finished. Assuming that both' clearing out drops have been operated, the circuit ,thus closed is from battery C, conductor 1, conductors 16a and 16^ to both of the sleeve terminals, thence to both lines A through the several instruments to the lines B, thus restorin(r all the instruments to normal, thence to the tip terminals and the tip conductor which -is connected with the ground through the conductors 17, 18 and 19.

While the construction and arrangement herein shown and described constitute a .thoroughly practical embodiment of the invention, it is not intended to limit the invention tolthe specific constructlon and ar- This locks out the inrangement shown, since it is obvious that material modifications may be made Without de arting from the invention.

laims.

1. In a signaling system, an electro-magnet provided with a polarized armature and a signaling device operated by the vibration of said armature; means for preventing the vibration of said armature; a second armature in the field of said electro-magnet ada ted by its movement to operate the means orY preventing the vibration of the polarized armature; a third armature to control the res torin'goi1 the preventing means to normal; and means for energizing said electro-magnet by direct currents and by alternating currents, substantially as described.

2. In a signaling system; the combination with an electro-magnet Lprovided with a' polai'ized armature adapte tooperate a signaling device; of a non-polarized armature adapted to respond only to thev action of a direct current through said electro-magnet;. a llocking device for controlling the. polarized armature adapted to be operated by the movement of said non-polarized armature; a

` second polarized armature; a restoring device controlled by said second polarized armature; means or preventing the said sccond polarized armature from responding to an alternating current; andm`eans for energizing said electro-magnet by current in either direction or by'an alternatingcurrent, substantially as and for the purpose described.

3. In a party line telephone system, an electro-magnet bridged across the line at each station thereon; means located at central Oiiice for energizing said electro-magnet by 'impulses-of direct current in either direction;

a controlling device' adapted to be operated by the magnetic influence of saidV electromagnet in response to impulses of current in one direction; av restoring device for the same operating in response to an impulse of current in the other direction; a

vibrating armature controlled .by said controlling device and adapted When not prevented I`by said contro ling device to` be vibrated by an alternating current passing vthrough said electro-magnet; and means located at central office for sending an alternating current overithe-vline, as set forth'. e

4. In a partylinetelephone system, a telephone circuit including-a number of stations a si aling device at eacnstation; a locking device to prevent the closure of the said circuit ata station; a locking device to prevent the operation of the signaling device Yat astation; a single electro-magnet bridged across the line and provided with an armaturefor operating said locking devices and an armature for, operating said signaling device; means for sending impulses of direct current through saidelectro-magnet from the central office to cause the o eration of said locking devices; and means Aor sending an alternating current through said electro-magnet from central oice to operate the signaling device,

-as set forth.

5. yIn a party line telephone system, the combination with an electro-magnet bridged across the line at c ach station; of asource of direct current located at centraloce means for connecting the said source of direct current with the line conductors Wherebiythe several electro-magnets are energized; means ior reversing the direction of the current from said source; asource of alternating current; means for connectinor the line conductors with said source of aIternatin current; armatures in the field 'of said e cetro-magnet 'and arranged lrespectively to respond to currents sent over the line of different direction; and a separate armature`responsive to alternating currents for signaling, as described.

6. In a signaling device for party line teley phones, an electro-magnet brid ed across the line at each station; a non-p0 arized arma-l ture under theiniiuence of said electro-magnet;vr a controlling device adapted to be operated lby said nonolarized armature; a polarized armature a so under the iniiuence ofsaid electro-magnet; `a` restoring device controlled by said polarized'armature means connected with the non-polarized armature for locking/said polarized armature in a predetermined position; a second polarized' arlmature connected with a signaling device; and means for connecting the line conductors with a source of `alternating current to influence the said second polarized armature, as set forth.

7. The combinationv with the coils c, ofthe polarized armature b provided with the bellstriker d, the locking disk e; the non-polar- !ized armature f2 adapted to operate said locking disk, thepolarized armature g2 for restoring said lookin disk; means connected I with the armature 2 for locking said polarized armature g2; a source of direct currents; a source .of alternating currents; means for connecting the line conductors With either terminal of the source of direct current; and v means for energizing said electro-magnet by direct currents in either direction to operate said mechanical device; and means for energiz'ing the same electro-magnet by an alter nating current to operate the signaling device.

9. In a party line telephone system, a plurality of stations on one line; an electro-mag'- net at each station; a polarized signaling armature in thefield of said electro-magnet; a locking stop to engage mechanically either side of said armature and prevent the same from vibrating, except when said stopis in a predetermined position, such predetermined positions differing respectively at the 4several stations; and means located, at the central oflice lfor moving said stops in unison, as set forth. l

10. Ina party line tele hone system, the combination with a plura ity of stations, of the switch hook at each station; a telephone circuitleading to the several stations; a separate circuit controlled by each of said switch hooks,v said circuit including all the.Y stations on the same line; and a device located at each station and operated'in response to the current flowing through the lseparate circuit above named for preventing the movement of the switch hook at said station, as set forth.

.11. In avparty line telephone system, a

- central station; a plurality olstations on a single line; a telephone at each station; a telephone circuit; means located at each station forclosing the telephone circuit; a source of current located at the central ollce a separate circuit therefor adapted to be momentarily' closed by the means lor closingi the. vtelephone circuit aforesaid; and devices operated by current flowing over said separate circuit for preventing the other telephones on thesaine line from being connected witlrcentral oflice.

'. controllers operated by electro-magnets;

. current; and

12. In a party line telephone system, a sign aling circuit at each station; a' l signaling device operated by a vibrating armature in response to current flowing through said circuit; means for mechanically engaging either side of said armature to prevent the signaling device from o eratine in response to such evices zlocated at the central oflice-for operating the engaging means.

13. Ina party line telephone system, a telephone line circuit having a plurality of stations; a. switch hook at each station; a se arate circuit including all the stations and a apted to be momentarily closed by the movement of said switch hook'to send an impulse lof current to each station; and a device located at each station under theinfluenceV of current flowing through said separate circuit for preventing theclosure of the telephone circuitat the station where said de. vice is located. v

14. In a partylinel telephone system, the combination with the two conductors of the line circuit; of a third conductor; a series of.

means for operating said'controllers by current flowing in one direction; means for restoring said controllers by current flowing in the, opposite direction means for energizing said electro-magnets by current (lowing over a circuit including said third conductor; a cord circuit at thc central ollce; and means depending upon th'c insertion of the cord circuit plug at central for controlling the direction of current.

15. In a party line telephone system, the combination with the two conductors of the line circuit; ofa ythird conductor extending from central ollice to theseveral stations; a series ol" electro-magnets bridged across the two conductors of the line circuit; controllers operated by said electro-magnets; a source ol- .current one terminal of which is connected to said third conductor; and means f or connecting the said third conductor with one of the line conductors and the other line conductor to the other terminal of said source of current to energize said electro-magnets; as set forth.

16. In a party line telephone system, the. combination withthe two conductors of the line circuit; of' controlling magnets bridged. across thelineateachstation; a source of current at the central ollice; a third conductor connected with one terminal of said source; and means vfor,.,connecting one of the two conductors of thelne circuit with saidA third conductor andthe other conductor of the line circuit with the othertern'iinal of the said source to energize the several electromagnets, substantiallyas dcscribed 17.'In a'party line telephone system, the combination with' the two conductors of the line circuit; fan electro-niagi'iet,bridged across betwcen'the two conductors at cach station; .controlling 'jjd'evices operated by current flowing throi'igh'- said electro -magnets; a source of' current located yat central office and having one'of its terminals normally connected with one ofthe line con-` ductors and its other terminal grounded;` and means for grounding the other line conductor to close a circuit through the several electro-inagnets, as set forth.

18. In a party line telephone system, the combination with the 4two line conductors; of an electro-magnet for controlling purposes' bridged across the line at each station;l a source of current located; at the central oflice a third conductor such as a ground leading tov the several stations from one terminal of the said source of current, the other terminal being normally connected with one of the line conductors; means' located at each station for momentarily connecting the other line conductor with the other terminal of said source of current toclose a circuit through the several electro-magnets; and a 'signaling device at central office, having a controlling electro-magnet located in the circuit thus momentarily closed, as set forth.l

19. In a` party line telephone system, the combination with the two line conductors; of an electro-magnet for controlling purposes bridged across the line at each station; a

source of current located at the central office; a third conductor such asa ground leading to the several stations from one terminal of the said source ofv current, the other terminal being normally connected with one of the line conductors; means located at each station for momentarily connecting the other line conductor with the other terminal of said source of current to close a circuit through theseveral electroniagnets; a' signaling device at central olicehaving a controlling electro-magnet located in the circuit thus momentarily closed; and means operated by said signaling device for 'breaking the said circuit, as set fortln 20. In a party line telephone system, the combination with tlie controlling device at each instrument; and means for restoring said controlling device to'iiornial in response to an impulse of current in a given direction; of a kclearing-out signal for each line; a circuit controlling said clearing-out signal;

means under control of the subscriber for closing the said .circuit momentarily to actu.- ate the clearing-out signal and a circuit controlled by both clearing out signals of two connected lines, the closure of said circuit causing current to iiow through the several controlling magnets in a direction to restore the controlling devices, as setlfortli.

21. In a party line telephone system, a controlling device at each station; a source of current at central office for operatingthe controlling device; a set of connecting cords at central oiiice each provided with a circuit closer or table key; vmultiple circuits including the sourcerof current and the controlling devices, each-of said circuits being controlled by one of the circuit closers aforesaid; and a single circuit closer coinnion to all of said multiple circuits.

22. In a party line telephone system, a controller at each st ation; a calling signal at central office; means for actuating the severall controllers and said calling signal by an impulse ofcurrent iii one direction; and means for'restoring to normal said controllers and said calling signal by an .impulse of current in the opposite direction.

2S. In a 'party line telephone system, a

controller at each'station; a calling signal at each station; means for operating said coni' trolling device'by current iiowing in one'direction and for restoring said controlling deviceby current flowing in the opposite direction; a -source of current at the central otlice means located at the central office for connecting either line conductor with either terminalot the source of current; a third conductor connected with one terminal of said source of current; and means located at each station for connecting one sidev of the line with said third'conductor.

In testimony whereof, .we have signed our naines to this specification in .the presence of two subscribing witnesses.

' FRANK E. MAYBERRY. w

NEWMAN H. HOLLAND.` Witnesses:

NANCY- P. Form, v HENRY J. LIVERMORE. 

